Liquid pharmaceutical compositions are convenient dosage forms for oral administration particularly for geriatric and pediatric patients in comparison to solid dosage forms such as tablets and capsules. They are easy to administer which leads to enhanced patient compliance. Additionally, liquid pharmaceutical compositions provide a unique advantage of having a flexible dosing regimen. Liquid pharmaceutical compositions are generally in the form of a solution or a suspension, wherein the active ingredient remains in the dissolved or dispersed form in a pharmaceutically acceptable vehicle such as water.
However, some of the active ingredients remain unstable in the presence of pharmaceutically acceptable vehicle such as water when stored for a prolonged period of time. To overcome this, the active ingredients are mostly formulated as a dry powder which is to be reconstituted with the pharmaceutically acceptable vehicle at the time of administration. The reconstitution is done by the end user, wherein the dry powder is dissolved or suspended in household pre-boiled and cooled water to form a liquid pharmaceutical composition. Alternatively, the pharmaceutically acceptable vehicle or purified water is supplied separately along with the bottle having the dry powder. This conventional pack lacks patient compliance and may lead to contamination due to improper quality of water. Further, there remains a possibility of dosing errors if the pharmaceutically acceptable vehicle or water is not added to the marked level.
U.S. Pat. Nos. 1,156,369; 3,601,469; 3,840,136; and 4,982,875 disclose the use of dual-chamber packs for separately storing two compositions in two compartments which can be admixed at the time of use. The two compartments are separated by a breakable membrane which is ruptured by the depression of a plunger so that the one composition gets released into another and is mixed. However, there remains a possibility that the membrane fragments may get detached and fall into the final product. This may lead to undesirable contamination and can pose serious health hazards. Furthermore, the dual-chamber packs disclosed in the prior art have a limited capacity for the compartments which may not be suitable for high-dose drugs or for drugs which require chronic administration. Also, the liquid composition may get permeated into the solid composition across the membrane during storage which can lead to the agglomeration of the solid composition. This may result in poor flow of the solid composition, thus affecting the content uniformity of the final product. Also, the liquid composition on permeation can affect the stability of moisture-sensitive drugs.
The present invention provides a patient compliant dual-chamber pack with a significant improvement over the prior art and which fulfills the unmet need of incorporating variety of drugs. The present dual-chamber pack can be suitable for any class of drugs including the high-dose drugs, drugs requiring chronic administration, or moisture-sensitive drugs. Multi-dose liquid compositions can be conveniently administered using this pack. Further, the plunger used in the pack of the instant invention is designed in a way such that the breakable membrane remains adhered to the plug at the time of activation and membrane fragments do not fall into the final product. During activation, the pack ensures that the final product remains safe for the use of patients. The pack also ensures that the solid composition is completely released into the liquid composition thereby maintaining the content uniformity of the final product. Further, the pack also ensures that there is no permeation of moisture into the chamber having solid composition comprising the active ingredient, and the stability of the active ingredient remains unaffected during storage.